A part of the human body only present in the development of the urinary and reproductive organs

<span class="mw-page-title-main">Urogenital sinus</span>

Urogenital sinus

<p>The <b>urogenital sinus</b> is a part of the human body only present in the <a href="/en/Development_of_the_urinary_and_reproductive_organs" title="Development of the urinary and reproductive organs" class="mw-redirect wl">development of the urinary and reproductive organs</a>.  It is the ventral part of the cloaca, formed after the <a href="/en/Cloaca_(embryology)" title="Cloaca (embryology)" class="wl">cloaca</a> separates from the <a href="/en/Anal_canal" title="Anal canal" class="wl">anal canal</a> during the fourth to seventh weeks of development.<span class="mw-ref reference" id="cite_ref-langman243-244_1-0"><a href="#cite_note-langman243-244-1" style="counter-reset: mw-Ref 1;"><span class="mw-reflink-text">[1]</span></a></span></p>

<div class="shortdescription nomobile noexcerpt noprint searchaux" style="display:none" about="#mwt1">A part of the human body only present in the development of the urinary and reproductive organs</div>
<style data-mw-deduplicate="TemplateStyles:r1066479718" typeof="mw:Extension/templatestyles mw:Transclusion">.mw-parser-output .infobox-subbox{padding:0;border:none;margin:-3px;width:auto;min-width:100%;font-size:100%;clear:none;float:none;background-color:transparent}.mw-parser-output .infobox-3cols-child{margin:auto}.mw-parser-output .infobox .navbar{font-size:100%}body.skin-minerva .mw-parser-output .infobox-header,body.skin-minerva .mw-parser-output .infobox-subheader,body.skin-minerva .mw-parser-output .infobox-above,body.skin-minerva .mw-parser-output .infobox-title,body.skin-minerva .mw-parser-output .infobox-image,body.skin-minerva .mw-parser-output .infobox-full-data,body.skin-minerva .mw-parser-output .infobox-below{text-align:center}</style><div class='mobile-collapse'><header class="mobile-collapse-header mobile-collapse-btn"><b>Quick facts: Urogenital sinus, Details, Carnegie stage, Pr...</b> <span class='arrow'>▼</span></header> <table class="infobox mobile-collapse-element"><tbody><tr><th colspan="2" class="infobox-above notheme" style="background-color:thistle">Urogenital sinus</th></tr><tr><td colspan="2" class="infobox-image"><span class="mw-default-size"><a href="/en/File:Gray1109.png" class="mw-file-description image media-thumb" data-hash="File:Gray1109.png"><img loading="lazy" src="//upload.wikimedia.org/wikipedia/commons/thumb/6/6d/Gray1109.png/250px-Gray1109.png" decoding="async" data-file-width="371" data-file-height="400" data-file-type="bitmap" height="270" width="250" srcset="//upload.wikimedia.org/wikipedia/commons/6/6d/Gray1109.png 1.5x, //upload.wikimedia.org/wikipedia/commons/6/6d/Gray1109.png 2x" alt="Gray1109.png"></a></span><div class="infobox-caption">Urogenital sinus of female human <a href="/en/Embryo" title="Embryo" class="wl">embryo</a> of eight and a half to nine weeks old. (Urogenital sinus labeled at bottom.)</div></td></tr><tr><td colspan="2" class="infobox-image"><span class="mw-default-size"><a href="/en/File:Development_of_external_sexual_organs_in_the_male_and_female_Gray1119.png" class="mw-file-description image media-thumb" data-hash="File:Development_of_external_sexual_organs_in_the_male_and_female_Gray1119.png"><img loading="lazy" src="//upload.wikimedia.org/wikipedia/commons/thumb/0/07/Development_of_external_sexual_organs_in_the_male_and_female_Gray1119.png/250px-Development_of_external_sexual_organs_in_the_male_and_female_Gray1119.png" decoding="async" data-file-width="579" data-file-height="691" data-file-type="bitmap" height="298" width="250" srcset="//upload.wikimedia.org/wikipedia/commons/thumb/0/07/Development_of_external_sexual_organs_in_the_male_and_female_Gray1119.png/375px-Development_of_external_sexual_organs_in_the_male_and_female_Gray1119.png 1.5x, //upload.wikimedia.org/wikipedia/commons/thumb/0/07/Development_of_external_sexual_organs_in_the_male_and_female_Gray1119.png/500px-Development_of_external_sexual_organs_in_the_male_and_female_Gray1119.png 2x" alt="Development_of_external_sexual_organs_in_the_male_and_female_Gray1119.png"></a></span><div class="infobox-caption">Stages in the development of the external sexual organs in the male and female. ("Opening of urogenital sinus" labeled in diagram D.)</div></td></tr><tr><th colspan="2" class="infobox-header notheme" style="background-color: #efefef">Details</th></tr><tr><th scope="row" class="infobox-label" style="padding-right:0.25em"><a href="/en/Carnegie_stages" title="Carnegie stages" class="wl">Carnegie stage</a></th><td class="infobox-data"><a rel="mw:ExtLink nofollow" href="http://genex.hgu.mrc.ac.uk/Databases/HumanAnatomy/new/carnegie15.shtml" class="external text" target="_blank">15</a></td></tr><tr><th scope="row" class="infobox-label" style="padding-right:0.25em"><a href="/en/Embryology" title="Embryology" class="wl">Precursor</a></th><td class="infobox-data"><a href="/en/Cloaca_(embryology)" title="Cloaca (embryology)" class="wl">Cloaca</a></td></tr><tr><th scope="row" class="infobox-label" style="padding-right:0.25em"><a href="/en/Embryology" title="Embryology" class="wl">Gives rise to</a></th><td class="infobox-data"><a href="/en/Urethra" title="Urethra" class="wl">urethra</a>, <a href="/en/Urinary_bladder" title="Urinary bladder" class="mw-redirect wl">bladder</a>, <a href="/en/Vagina" title="Vagina" class="wl">vagina</a></td></tr><tr><th colspan="2" class="infobox-header notheme" style="background-color: #efefef">Identifiers</th></tr><tr><th scope="row" class="infobox-label" style="padding-right:0.25em"><a href="/en/Latin" title="Latin" class="wl">Latin</a></th><td class="infobox-data"><i>sinus urogenitalis definitivus</i></td></tr><tr><th scope="row" class="infobox-label" style="padding-right:0.25em"><a href="/en/Terminologia_Embryologica" title="Terminologia Embryologica" class="wl">TE</a></th><td class="infobox-data"><a rel="mw:ExtLink nofollow" href="https://ifaa.unifr.ch/Public/EntryPage/THE/TE2010V1.pdf#page=74?note=Linked_from_Urogenital" class="external text" target="_blank">sinus_by_E5.7.3.1.0.0.1   E5.7.3.1.0.0.1  </a></td></tr><tr><td colspan="2" class="infobox-below"><a href="/en/Anatomical_terminology" title="Anatomical terminology" class="wl">Anatomical terminology</a><div style="text-align: right;"><small class="noprint">[<a href="https://www.wikidata.org/wiki/Q5251638" title="d:Q5251638" class="extiw" target="_blank">edit on Wikidata</a>]</small></div></td></tr></tbody></table> <footer class='mobile-collapse-footer mobile-collapse-btn'><b>Close</b> <span class='arrow'>▲</span></footer></div>

<p>In males, the UG sinus is divided into three regions: upper, pelvic, and phallic.   The upper part gives rise to the <a href="/en/Urinary_bladder" title="Urinary bladder" class="mw-redirect wl">urinary bladder</a> and the pelvic part gives rise to the prostatic and membranous parts of the <a href="/en/Urethra" title="Urethra" class="wl">urethra</a>,<span class="mw-ref reference" id="cite_ref-langman243-244_1-1"><a href="#cite_note-langman243-244-1" style="counter-reset: mw-Ref 1;"><span class="mw-reflink-text">[1]</span></a></span> the prostate and the bulbourethral gland (Cowper's). The phallic portion gives rise to the spongy (bulbar) part of the urethra and the urethral glands (Littre's). Note that the penile part of the urethra originates from urogenital fold.</p>

<p>In females, the pelvic part of the UG sinus gives rise to the <a href="/en/Sinovaginal_bulb" title="Sinovaginal bulb" class="wl">sinovaginal bulbs</a>, structures that will eventually form the inferior two thirds of the <a href="/en/Vagina" title="Vagina" class="wl">vagina</a>.  This process begins when the lower tip of the <a href="/en/Paramesonephric_ducts" title="Paramesonephric ducts" class="mw-redirect wl">paramesonephric ducts</a>, the structures that will eventually form the <a href="/en/Uterus" title="Uterus" class="wl">uterus</a> and <a href="/en/Vaginal_fornices" title="Vaginal fornices" class="mw-redirect wl">vaginal fornices</a>, come in contact with the UG sinus.  Shortly afterwards, the <a href="/en/Sinovaginal_bulb" title="Sinovaginal bulb" class="wl">sinovaginal bulbs</a> form as two solid <a href="/en/Evagination" title="Evagination" class="mw-redirect wl">evaginations</a> of the UG sinus. Cells in these bulbs divide to form a solid <a href="/en/Vaginal_plate" title="Vaginal plate" class="mw-redirect wl">vaginal plate</a>, which extends and then canalizes (hollows) to form the inferior portion of the <a href="/en/Vagina" title="Vagina" class="wl">vagina</a>.<span class="mw-ref reference" id="cite_ref-langman253_2-0"><a href="#cite_note-langman253-2" style="counter-reset: mw-Ref 2;"><span class="mw-reflink-text">[2]</span></a></span> The female urogenital sinus also gives rise to the urethra and vestibule of the vagina.</p>



The urogenital sinus is a part of the human body only present in the development of the urinary and reproductive organs.  It is the ventral part of the cloaca, formed after the cloaca separates from the anal canal during the fourth to seventh weeks of development. In males, the UG sinus is divided into three regions: upper, pelvic, and phallic.   The upper part gives rise to the urinary bladder and the pelvic part gives rise to the prostatic and membranous parts of the urethra, the prostate and the bulbourethral gland . The phallic portion gives rise to the spongy part of the urethra and the urethral glands . Note that the penile part of the urethra originates from urogenital fold. In females, the pelvic part of the UG sinus gives rise to the sinovaginal bulbs, structures that will eventually form the inferior two thirds of the vagina.  This process begins when the lower tip of the paramesonephric ducts, the structures that will eventually form the uterus and vaginal fornices, come in contact with the UG sinus.  Shortly afterwards, the sinovaginal bulbs form as two solid evaginations of the UG sinus. Cells in these bulbs divide to form a solid vaginal plate, which extends and then canalizes to form the inferior portion of the vagina. The female urogenital sinus also gives rise to the urethra and vestibule of the vagina. 